A carrying device of the type is known from U.S. Pat. No. 4,844,387. Two bracket legs, which are connected to the head pieces in an articulated manner, are arranged between two end-side head pieces in the form of a parallelogram cranking mechanism. To compensate the weight of an object being carried, an opposing force means in the form of a pneumatic spring is provided, which ensures that the height of the object being carried can be set in a predetermined position with the parallelogram cranking mechanism. The pneumatic spring is self-locking and has a valve, by which the pneumatic spring is released. The valve can be actuated via a pushbutton arranged laterally on the bracket.
One of the head pieces is attached to a table or desk with a cranking mechanism, while a device mount for a monitor is arranged at the other head piece. The monitor can be set to the desired working height with a handle on the front side of the device mount. By actuating the pushbutton on the bracket, the self-locking of the pneumatic spring is abolished for this. Such brackets are also used in medical treatment rooms to mount monitoring devices. The monitoring device can be positioned at the eye level of the user in a simple manner by means of the freely swiveling parallelogram cranking mechanism.
The drawback of the prior-art carrying device is that two hands are needed for the adjustment, one of which swivels the device mount while the other actuates the pushbutton.
A height-adjustable bracket with a parallelogram cranking mechanism between two head pieces and with a self-locking pneumatic spring, in which [spring] the self-locking can be abolished with a hydraulic system, is known from DE 10 2004 026 117 B3. The hydraulic system has a hydraulic release element at the pneumatic spring, a release button and a hydraulic line between the hydraulic release element and the release button.
The release button is arranged at a head piece of the bracket, and one-hand operation is not solved satisfactorily in combination with an additional supply unit for medical devices. The prior-art hydraulic system is suitable for pneumatic springs of a small size only because of the forces to be transmitted.